1. Field of the Invention
The present invention relates to a novel 1,4-dihydropyridine-5-phosphonic acid cyclic propylene ester, a process for the preparation thereof, and an antihypertensive agent or coronary or peripheral vasodilator composition containing the novel ester or its pharmaceutically acceptable salt.
2. Description of the Prior Art
1,4-Dihydropyridines are known to be useful for the medical treatment of coronary heart diseases, cerebral diseases, hypertension or arrhythmia, as they are capable of inhibiting the contraction of smooth muscle and cardiac muscle by calcium antagonistic effects (see A. Fleckenstein, Annu. Rev. Pharmacol. Toxicol., 17, 149-166 (1977)). However, the majority of 1,4-dihydropyridines known or being developed are substituted at the 3- and 5-positions by a carboxylic acid ester group.
Dihydropyridine-5-phosphonate derivatives are disclosed in prior art references. However, none of them suggests or indicates the specific compounds of the present invention.